Selective sulfonation procedure for separating a 1, 3, 5-trialkylbenzene from benzene hydrocarbons



trated. sulfuric acid United States Patent SELECTIVE SULFONATION PROCEDURE FOR SEPARATING A 1,3,5-TRIALKYLBENZENE FROM BENZENE HYDROCARBONS Ben Bennett Corson and burgh, Pa., assignors to Koppers Company, poration of Delaware No Drawing. Application February 24, 1956 Serial No. 567,484

7 Claims. (Cl. 260-674) Inc., a cor- 1 2,873,300 Patented Feb. 10, 1959 2 determined that a minimum of about 1.9 moles of concentrated sulfuric acid per mole of impurity and up to about 1 mole of concentrated sulfuric acid per mole of total hydrocarbon is required to obtain a 1,3,5-trialkyl- 5 benzene raffinate ranging in purity from about 90% to Louis H. Schwartzman, Pittsr kylbenzenes containing a 1,3,5-trialkylbenzene, together with one or more other alkylbenzenes having up to three alkyl substituents is subjected to sulfonation with a stoichiometric excess of concentrated sulfuric acid over that needed to sulfonate the other alkylbenzenes and up to about equimolar proportions, based on total hydrocarbon, sulfonation of said other hydrocarbons, hereinafter called impurities, takes place to the substantial 100% when a preferred sulfonation temperature range of from about 110 C. to about 140 C. is used. Within such preferred sulfonation temperature range, the molar ratio of H to 1,3,5-trialky'lbenzene lies between about 0.3 and about 1.9. Advantageously, a sulfonation temperature ranging from about 50 C. to about 200 C. can be used. Such temperatures of sulfonation outside the preferred range of 110 C. to about 140 C. require a longer reaction time within the range 50 C. to 110 C. and a shorter reaction time within the range 110 C. to 200 C.

The recovery and purity of 1,3,5-trialkylbenzene suffer when less than about1.9 moles of concentrated sulfuric acid per mole of impurity is used. Greater amounts of concentrated sulfuric acid than equim-olar proportions, based on total hydrocarbon, result in sulfonation and decreased yield of the 1,3,5-trialkylbenzenes, as in Example 1, runs 3 and 8.

The selective sulfonation procedure separates the indicated 1,3,5-trialkylbenzenes from any other impurities having up to three alkyl substituents, whether primaryand/or secondaryand/or tertiary-alkyl. The sulfonated products, preponderantly monosulfonates, can be recovered and used.

The following examples are an illustration of, and not in limitation of, this invention, which is defined in the claims. The various alkylbenzene contents are determined by infrared spectrometry.

EXAMPLE 1 Separation of ethyldimethylbenzenes by selective sulfonation Hydrocarbon Sulfuric Acid Recovery of 1 ethyl 3,5-di- R 1 th 1 1 n1 1 1 th 1 m H TC methylbenzene HI! 0 y 8 Y e y TS.

Total 3,5-di- 2,4-di- 2,5-di- Total H1804 1 BthY13-5 H1801 Moles methyl methyl methyl Moles in. H0 dimethylbenm. Impurities Percent Percent zene Yield Purity .0 77 9 10 1. 0 1. 0 1. s 4. 3 1. 0 110 93 99 0 71 9 10 0. 25 0. 25 0. 32 1. 1 1. 0 140 93 83 .0 73 10 12 2. a 2. 3 a. 2 s. 5 1.8 110 10 99 .0 73 10 12 0. 52 0. 52 0. 7 1. 9 2. 0 140 99 .0 65 28 7 1. 0 1. 0 1. 5 2. 9 1. 0 110 97 .0 65 2s 7 1.0 1.0 1.5 2.9 1.0 140 95 95 65 22 13 655 1. 0 1. 5 2. 0 4. 0 1110 90 93 .45 5s 26 15 0. 5 1. 1 1. 9 2. 0 2. 0 1110 66 100 exclusion of the 1,3,5-trialkylbenzene. Any 1,3,5-trialkylbenzene can, accordingly, be separated as a raifinate phase from such impurities as indicated above, provided that the 1,3,5-trialkylbenzene contains only primary and/or secondary alkyl radicals. Tertiary-alkyl radicals are removed under reaction conditions and, therefore,

.1,3,5-trialkylbenzenes containing one or more tertiary-- alkyl radicals cannot be separated from other alkylbenzenes by our process.

The selective sulfonation procedure utilizes a concencontaining about 94%-96% of H 80 Within the scope of this invention it has been zene and l-ethyl 2,5-dimethylbenzene give substantially,

similar recoveries of l-ethyl 3,5-dimethylbenzene. Y

EXAMPLE 2 Separation of c -aromatic hydrocarbon mixture by se lective sulfonction [Hydrocarboncharge77% mesitylgne 9% pseudoeuniene 3% hemimellltene and j I When l-is opr opyl 2,4-dimethy1benzeneand -1-isopropyl 2,5-dimethylbenzene are substituted in equimolar amount forthe pseudocurneneand hemimellitene above, equally high recoveries of pure mesitylene are obtained.

, 1 I Mesitylene Recovery 1 H0 111. H2804 H SO I m. H2804 T 0 H m. m. 4 rs.

, 1n. HO 2 m. Mesltylene Yield Purity, percent percent I 1,3,5-tr1methy lbenzene. b 1,2,4-trimethylbenzene. 1,2,3-trlrnethylbenzenc.

stituents, the steps which include reacting said hydrocarbon, mixture, atabout 50 C.-200 C. with' concentrated sulfuric. acid containing from about 94 to 96% ofsulfun'c acid for a time sufficient and'in amount at least 1 IPOMBisopropyldhnethylbenzene.

The procedure of Example 1 is repeated with the above indicated results.

When toluene, l-ethyl 2,4-dimethylbenzene and 1- ethyl 2,5 dimethylbenzene are substituted in equimolar amount for the above-indicated l-isopropyl 2,4-dimethylbenzene and l-isopropyl 2,5-dimethylbenzene respectively, substantially equivalent recoveries of l-isopropyl 3,5- dimethylbenzene are obtained.

EXAMPLE 4 Concentrated sulfuric acid (96%, 150 lbs.) is added over one hour to a stirred mixture of isomeric ethyl xylenes (190.4 lbs., containing 65.2% l-ethyl 3,5-dimethylbenzene, 21.1% l-ethyl 2,4-dimethylbenzene, 11.8% l-ethyl 2,5-dimethylbenzene, and 1.1% l-ethyl 2,6-dimethylbenzene) kept at 110 C. The mixture is stirred at 110 C. for an additional three hours and then cooled to C. The acid layer is separated. The organic layer is washed for two minutes with 120 lbs. of water and separated. This process is repeated with 83 lbs.

When unsymmetric dnsopropylmethylbenzenes and unsymmetric diethylmethylbenzenes or unsymmetric triethylbenzenes are substituted in equimolar amounts for the unsymmetric ethylxylencs above, equally advantageous results are obtained.

, What is claimed is:

1. ha, selective sulfonation process for separating a 1,3,5-trialkylbenzene from alkylbenzene mixtures containing other alkylbenzenes having up to three alkyl subsutficient to sulfonate said other alkylbenzenes and up to substantially equimolar proportions, based on moles of total hydrocarbon, and separating a rafiinate 1,3,S-trialkylbenzene from the reaction medium, said 1,3,5-trialkylbenzene being free of tertiary-alkyl substituents.

2'.-,In-,a selective sulfonation process for separating a 1,3,5-trialkylbenzene from alkylbenzene mixtures containing other alkylbenzenes having up to three alkyl substituents', the steps whichinclude reacting said hydrocarbon mixture at about C., C. with concentrated sulfuric acid containingfrom about 94 to 96% of sulfuric acid for a time sufficientvand in amount at least sufii'cient to sulfonate said other alkylbenzenes and up to substantially equimolar proportions, based on moles of total hydrocarbon, and separating a raffinate 1,3,5-trialkylbenzene from the reaction medium, said .l,3,5-trialkylbenzene being free of tertiary-alkyl substituents.

3. Ina selective sulfonation process for separating a 1,3,5-trialky1benzene from alkylbenzene mixtures'containing other alkylbenzenes having up to three alkylsubstituents, the steps which include reacting said hydrocarbon mixture at a temperature of about 110 C.-140 C. with a substantially equimolar amount of concentrated sulfuric acid containing from about 94 to 96% of sulfuric acid, based on moles of total hydrocarbon, for a time sufficient to sulfonate said other alkylbenzenes, and separating a raffinate 1,3,5-trialkylbenzene from the reaction medium, said 1,3,5 -trialkylbenzene being free of tertiaryalkyl substituents. e

4. A selective sulfonation process for separating 1- ethyl 3,5-dimethylbenzene from alkylbenzene mixtures containing l-ethyl 2,4-dimethylbenzene and l-ethyl 2,5- dimethylbenzene which includes the steps of reacting said hydrocarbon mixture at about 110 C.140. C. with a substantially equimolar proportionof concentrated sulfuric acid containing from about 94 to 96% of sulfuric acid, based on moles. of total hydrocarbon,1for a time sufficient to sulfonate the other alkylbenzenes in said mixture and separating and recovering a rafiinate l-ethyl 3,5-dimethylbenzene.

5. A selective sulfonation process for separating 1,3,5- trimethylbenzene from alkylbenzene mixtures containing 1,2,3- and 1,2,4-trimethylbenzene and ethyltoluenes Which includes the steps of reacting said hydrocarbon mixture at about 110 C. with a substantially equimolar proportion of concentrated sulfuric acid containing from about 94 to 96% of sulfuric acid, based on moles of total hydrocarbon, for a time suflicient to sulfonate the other alkylbenzenes in said mixture and separating and recovering a raffinate 1,3,5-trimethylbenzene.

6. A selective sulfonation process for separating 1- isopropyl 3,5-dimethylbenzene from alkylbenzene mixtures containing l-isopropyl 2,4-dimethylbenzene and 1- isopropyl 2,5-dirnethylbenzene which includes the steps of reacting said hydrocarbon mixture at about 110 C. with a substantially equimolar proportion of concentrated sulfuric acid containing from about 94 to 96% of sulfuric acid, based on moles of total hydrocarbon, for a time suflicient to sulfonate the other alkylbenzenes in said mixture and separating and recovering a rafiinate l-isopropyl 3,5-dimethylbenzene.

References Cited in the file of this patent FOREIGN PATENTS Great Britain Nov. 24, 1947 OTHER REFERENCES Armstrong et al.: J. Chem. Soc. (1884), 153, page 151 only needed.

Mair et al.: J. Res. Nat. Bur. Standards, vol. 11, pages 665-680 (1933), page 676 only needed.

pages 148- UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 2,87%300 February 10, 1959 Ben Bennett Corson et a1.

It is hereby certified that error appears in the-printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Columns 1 and 2, Example 1, heading to eighth column, for

mu m P? SO 0 12 l 3"" e M m, 1 ethyl 305 dimeggii dimethylbenzene column 3, line 63, for "Ba P," read b0 p.

Signed and sealed this 2nd day of June 1959,

(SEAL) Attest:

KARL AXLINE ROBERT c. WATSON Attesting Oificer Commissioner of Patents 

1. IN THE SELECTIVE SULFONATION PROCESS FOR SEPARATING A 1,3,5-TRIALKYLBENZENE FROM ALKYLBENZENE MIXTURES CONTAINING OTHER ALKYLBENZENES HAVING UP TO THREE ALKYL SUBSTITUENETS, THE STEPS WHICH INCLUDE REACTING SAID HYDROCARBON MIXTURE AT ABOUT 50*C.-200*C. WITH CONCENTRATED SULFURIC ACID CONTAINING FROM ABOUT 94 TO 96% OF SULFURIC ACID FOR A TIME SUFFICENT AND IN AMOUNT AT LEAST SUFFICENT TO SULFONATE SAID OTHER ALKYLBENEZENES AND UP TO SUBSTANTIALLY EQUIMOLAR PROPORTIONS, BASED ON MOLES OF TOTAL HYDROCARBON, AND SEPARATING A RAFFINATE 1,3,5-TRIALKYLBENZENE FROM THE REACTION MEDIUM, SAID 1,3,5,-TRIALKYLBENZENE BEING FREE OF TERTIARY-ALKYL SUBSTITUENTS. 